Internal ASHP enquiry.

[Marvin]

Hi.

 

(sorry for my ignorance of terminology)

 

Requesting Help:

 

Before I go ahead and fit an internal ASHP (air to water) to my own home I wanted to know if its possible to purchase an internal ASHP unit separately form the hot water tank usually supplied to fit below. If so where from.

 

Just to confirm:

I am not interested in obtaining grants -  just installing the system I want. I am looking for a small unit of about 4kW input, with some hot water capability and if possible some cool air possibility in the summer, however I am open to alternative suggestions (I have a plan B to use excessive PV to cool the the bungalow in the summer)

 

The boring technical information for guidance is below. Any further info you need please let me know.

 

Thanks

 

 

Marvin 

 

 

 

Existing energy considerations:

Our bungalow has mains electricity.

No mains gas.

Bottled LPG for the gas boiler.

Very small amount of PV (to be increased...)

Whole house MVHR

Good insulation

Good air tightness.

 

 

Design considerations that effect the choice of ASHP :

We have a 3 year old existing central heating system run on LPG. The radiators are oversized.(about 50%)

We have a 205 litre hot water tank and the recent addition of my own design solar hot water (still tinkering around the edges but plenty of hot water unsupported for the last 10 days).

We are mildly effected by solar gain (even yesterday) although our windows and glazed doors only total about 18m2 but because of the thermal resistance of the building the heat gets      trapped a bit. We want to get rid of the gas boiler and replace with a ASHP and stay warm.

 

 

Positioning considerations an external ASHP 

After reading manufacturers installation instructions on various models we find there is no where externally that we are prepared to install an external unit for one of the following reasons:

 We live nearish to the sea (can hear it if the wind is in the right direction) 

 The wind can be quite strong and would effect the inlet outlet on a large fan however we can place the tubes from an internal ASHP elsewhere.

 Too near the neighbours bedrooms for us to be satisfied that we may cause a noise nuisance.

 Too far from the hot water tank to position outside because of the heat loss along the pipes.

 Flat roof too exposed to wind and rain. 

 

 

Heat requirement:

Our results show that the present total LPG energy used to heat our bungalow (100m2 bungalow) and water, is approximately 5800kW per year.

The results, when extrapolated from the temperatures down to -4C (degrees centigrade), also suggest a heating peak of 4kW (before any COP calculations are taken into affect) required for an internal temperature of 23C against an external temperature of -8C.

The calculated energy used to heat the building does not take into account the following: The added solar heat gain through windows, 3382kW per year used for all household electrical equipment most of which generates some heat (not including any EV charging), the now redundant (for a lot of the year) hot water requirement covered by the Solar water panels, and about 200 watts of heat per hour produced by us sitting in the building or about 280 watts per hour if were arguing. 

[ProDave]

Are you aware of such an "internal" ASHP?  And what are the "tubes" you refer to?

 

Apart from exhaust air heat pumps, all air source heat pumps have an outdoor unit.

[PeterW]

3 hours ago, Marvin said:

We live nearish to the sea (can hear it if the wind is in the right direction) 

No issue - a number of the manufacturers make the external units with coastal protection

 

3 hours ago, Marvin said:

The wind can be quite strong and would effect the inlet outlet on a large fan

It won’t - fans will more than cope even in strong winds 

 

3 hours ago, Marvin said:

Too near the neighbours bedrooms for us to be satisfied that we may cause a noise nuisance.

No noisier than a lot of other household items 
 

3 hours ago, Marvin said:

Too far from the hot water tank to position outside because of the heat loss along the pipes.

Insulate them on install like any boiler 

 

 

[Marvin]

37 minutes ago, ProDave said:

Are you aware of such an "internal" ASHP?  And what are the "tubes" you refer to?

 

Apart from exhaust air heat pumps, all air source heat pumps have an outdoor unit.

 

Thank you for your reply ProDave

 

I am aware of such internal ASHP's. Some have been indicated before on this site and I wondered if there were any updates.

 

It may be that there are some ASHP that don't have outdoor units which are not exhaust air heat pumps (I have MVHR installed and it works very well. (with 3 exceptions)

 

 

The tubes I refer to are of course the Inlet and exhaust (150mm diameter tubes)

 

Oh how technology moves on in the world! I've only just caught up with the (hot) benefits of solar hot water.

 

Regards

 

 

Phil.

 

 

 

[Marvin]

18 minutes ago, PeterW said:

No issue - a number of the manufacturers make the external units with coastal protection

 

It won’t - fans will more than cope even in strong winds 

 

No noisier than a lot of other household items 
 

Insulate them on install like any boiler 

 

 

 

Hi PeterW 

 

Thank you for your reply. I must admit our plans are based on what we would prefer.

 

I was quoting information I had read from various manufacturer's installation manuals like the Daikin altherma installation manual pages 7 and 8, which I assume may be out of date technologically by now?  I will look at other manufacturers installation details. Any particular ones you were thinking of?

 

Agreed that 35 to 50 decibels is not loud but 3 foot from an open bedroom window in summer is not the best arrangement.

 

The pipe distance issue is important to keep the coefficient of performance (COP) as good as possible during the coldest period of winter. Having looked at the heat loss from pipes outside the bungalow thermal envelope over about 16 metres one way, I think I would rather use a 4 bar fire in my living room. The complications of waterproofing pipe insulation underground to get to the bungalow is too much for my little brain. Whilst I think about it I understand that there is a 10 meter limit on the MCS 020 standard required to be met to avoid planning permission: https://www.microgenerationcertification.org/mcs-standards/installer-standards/

 

I will keep my options open but at the moment we are still looking at the inside ASHP option.

 

Kind Regards

 

 

Marvin

 

 

[ProDave]

12 minutes ago, Marvin said:

Agreed that 35 to 50 decibels is not loud but 3 foot from an open bedroom window in summer is not the best arrangement.

 

But in summer when the bedroom window is open, it will not be heating the house will it?  It will only be doing hot water heating, and use the timer so it does not do that while you are in bed.

 

My take on the noise thing.  My ASHP makes about the same level of noise as an oil boiler burner roaring away.  But people are happy to put an oil boiler inside the house so the noise it makes is inside the house, but seem to have a problem putting that same level of noise outside, just in case they might open a window and hear it?

[Marvin]

4 minutes ago, ProDave said:

But in summer when the bedroom window is open, it will not be heating the house will it?  It will only be doing hot water heating, and use the timer so it does not do that while you are in bed.

 

My take on the noise thing.  My ASHP makes about the same level of noise as an oil boiler burner roaring away.  But people are happy to put an oil boiler inside the house so the noise it makes is inside the house, but seem to have a problem putting that same level of noise outside, just in case they might open a window and hear it?

 

Thanks ProDave.

 

We're still thinking of using the ASHP to produce cooling in the summer (if this is possible) so I will look further at the internal ASHP at present.  Quite right though if we were wanting winter heating only.

[PeterW]

An internal ASHP or waste heat recovery ASHP can only really heat a hot water tank. ASHP technology takes a lot of air and the small amount of heat from it. To do that, you need big fans and big condensers and a lot of airflow. The smaller ones will give you 2-3kW heat at most, some even less. 

[Marvin]

16 hours ago, PeterW said:

An internal ASHP or waste heat recovery ASHP can only really heat a hot water tank. ASHP technology takes a lot of air and the small amount of heat from it. To do that, you need big fans and big condensers and a lot of airflow. The smaller ones will give you 2-3kW heat at most, some even less. 

 

Thanks PeterW for showing me my foolish thoughts!  (The only good thing is that I'm only looking for about 4kW)

 

Yes a few internal ASHP fitted with tanks - about £2-5k to buy on the market all heat up your bath/shower/tap water but forget trying to achieve the whole house. I note that most of the ones I looked at, I had to dig quite deep to find what the input/ output was and the result was often mired by the fact that it also had an emersion heater for those really cold or high demand moments. I note that GSHP's seem to have these as well, certainly what I have installed.

 

Marvin

[SteamyTea]

8 minutes ago, Marvin said:

note that GSHP's seem to have these as well, certainly what I have installed.

Probably for the unnecessary legionella cycle.

[Marvin]

AH yes! the over 60's kick.

 

 

[Marvin]

Can you buy 240v 28 day 16amp timers for the immersions nowadays?

[SteamyTea]

Just now, Marvin said:

Can you buy 240v 28 day 16amp timers for the immersions nowadays

I have some 7 day timer ones that have been controlling/limting my E7 for years.

Think I got them off Amazon.

[Marvin]

E7? sorry too thick to know what that is.?. but I was looking for 28 day. I was thinking of using a arduino system?? to control all the systems I have. (not even sure it can be done...)

[Marvin]

Do correctly sized radiators work ok when fed cool water using an ASHP? (Obviously with the right controls)

[A_L]

17 minutes ago, Marvin said:

Do correctly sized radiators work ok when fed cool water using an ASHP?

 

Yes, though their outputs are less.

 

Relative to 70°C outputs at 30°C/13.5%,  40°C/32.1%,  50°C/53.0%,  60°C/75.8% for rooms at 20°C and 'ordinary' radiators

 

[Marvin]

3 hours ago, A_L said:

 

Yes, though their outputs are less.

 

Relative to 70°C outputs at 30°C/13.5%,  40°C/32.1%,  50°C/53.0%,  60°C/75.8% for rooms at 20°C and 'ordinary' radiators

 

Thanks A_L  I have 50% over sized radiators installed because I was not sure that the insulation and MVHR would work as well in practice as in theory. It does. ?

 

Who says 2 wrongs don't make a right? ?